In-molded resistive and shielding elements

ABSTRACT

An article of manufacture having an in-molded resistive and/or shielding element and method of making the same are shown and described. In one disclosed method, a resistive and/or shielding element is printed on a film. The film is formed to a desired shape and put in an injection mold. A molten plastic material is introduced into the injection mold to form a rigid structure that retains the film.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/191,825, filed Aug. 14, 2008, which is acontinuation-in-part of U.S. patent application Ser. No. 12/106,250,filed Apr. 18, 2008, which claims priority to, and the benefit of U.S.Provisional Patent Application Ser. No. 60/925,421, filed Apr. 20, 2007,all of which are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present disclosure relates to touch sensitive switches, and moreparticularly, to capacitive switches that are molded in a plasticstructure. The present disclosure further relates to in-molded resistiveand shielding elements.

BACKGROUND

Touch sensitive switches are used in applications such as homeappliances (e.g., touch panels on stoves, washers and dryers, blenders,toasters, etc.), and portable devices (e.g., IPOD, telephones). Typicaltouch sensitive switches utilize resistive film sensing or capacitivesensing. Resistive film sensing utilizes two conductive resistive platesthat are separated by a very thin spacer. When a light force is appliedto one of the plates contact is made with the other plate and theresistance of the system increases. This in turn increases the voltageand can be used to provide an output. This type of technology can beused for single outputs as well as slider switch type outputs. Thedrawback to this type of switch is that it relies on the elasticproperties of the film (and spacer, adhesives, etc.) to return to aknown state when the force is removed.

Capacitive switching detects changes in capacitance due to a switchingevent, such as the placement of an object or a finger proximate to or incontact with the switch. Capacitive switches differ from the resistiveapproach above because they require substantially no force to realizeswitch activation. The actual sensitivity of this type of switch can betuned via a detection circuit. Capacitive switches beneficially provideimmunity to interference and eliminate the need for electro-mechanicalswitch gear (e.g., pushbuttons or sliding switches). In addition,because there are no moving parts, the failure rate is low. However,known techniques for manufacturing capacitive switches are notwell-suited to integrating the switches into three-dimensional supportstructures (e.g., user interfaces such as control panels). In addition,known capacitive switches cannot be readily integrated into structureshaving contoured shapes without the use of difficult assembly andalignment processes. Thus, a need has arisen for a capacitive switchthat addresses the foregoing. A similar need has arisen for in-moldedresistive and shielding elements.

SUMMARY

An article of manufacture having an in-molded capacitive switchcomprises a film and a plastic support structure. The film has a frontsurface and a back surface and at least one conductive ink sensing zoneprinted on the back surface. The film is secured to the plastic supportstructure such that the back surface of the film faces the plasticsupport structure. In one embodiment, at least a portion of the frontsurface of the film is exposed. In another embodiment, at least oneconductive ink sensing zone is not exposed. In a further embodiment,indicia relating to the function of the capacitive switch is printed onthe back surface of the film and is visible on the front surface of thefilm.

A method of making an article of manufacture having an in-moldedcapacitive switch comprises providing a film having a front surface anda back surface, applying a conductive ink sensing zone on the backsurface, and forming the film into a desired shape. The film ispreferably disposed in an injection mold having an interior such thatthe conductive ink sensing zone faces into the interior of the mold.Molten plastic is flowed into the injection mold to create a plasticsupport structure attached to the film, thereby creating the article. Inone embodiment, the conductive ink sensing zone does not contact any ofthe surfaces of the mold. In another embodiment, at least one connectoris molded into the article of manufacture such that it is electricallyconnected to the at least one conductive sensing element. In anotherembodiment, the step of forming the film into a desired shape comprisesvacuum thermoforming. In a further embodiment, the step of forming thefilm into a desired shape comprises high pressure forming.

An article of manufacture is provided that has an in-molded resistiveand/or shielding element. A film has a front surface and a back surfaceand at least one resistive and/or shielding element is printed on thefront or back surface. The film is secured to a plastic supportstructure such that the front or back surface of the film faces thefront surface or back surface of the plastic support structure. In oneembodiment, at least a portion of the front or back surface of the filmis exposed. In another embodiment, at least one resistive or shieldingelement is not exposed. In a further embodiment, indicia relating to thefunction of the article of manufacture is printed on one surface of thefilm and is visible on the other surface of the film.

A method of making an article of manufacture having an in-moldedresistive and/or shielding element is also provided. This methodincludes the steps of providing a film having a front surface and a backsurface, applying a resistive or shielding element on the front or backsurface, and forming the film into a desired shape. The film is insertedin an injection mold having an interior. Molten plastic is flowed intothe injection mold to create a plastic support structure attached to thefilm, thereby creating the article.

The film can be inserted such that the resistive element or shieldingelement faces into the interior, away from the interior, or isin-between the top and bottom of the injection mold. This allows all, aportion, or none of the film to be exposed. In addition, the front orback surface of the film can be coated with a dielectric layer. Further,either the front surface or the back surface of the film can be disposedso as to face the front surface or back surface of the molded part.

In one embodiment, the resistive or shielding element does not contactany of the surfaces of the mold. In yet another embodiment, at least oneconnector is molded into the article of manufacture such that it iselectrically connected to the at least one resistive or shieldingelement. In another embodiment, the step of forming the film into adesired shape comprises vacuum thermoforming. In a further embodiment,the step of forming the film into a desired shape comprises highpressure forming or hydroforming.

In one embodiment, applying the ink layer includes applying a conductiveadhesive on the terminal block pin(s) by hand or robotic process and/oras a printed layer using a printer.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing brief description, as well as further objects, featuresand advantages of the present invention will be understood morecompletely from the following detailed description of presentlypreferred embodiments, with reference being had to the accompanyingdrawings in which:

FIG. 1 is an exploded view of a film switch including a conductive inksensing zone used to form an in-molded capacitive switch.

FIG. 2A depicts one embodiment the film of FIG. 1 following a formingoperation;

FIG. 2B depicts one embodiment the film of FIG. 1 following a formingoperation;

FIG. 3 depicts a cross-section of an article of manufacture having anin-molded capacitive switch;

FIG. 4 is a perspective view of an article of manufacture having anin-molded capacitive switch used to depict the attachment of connectorterminals;

FIG. 5 is a plan view of a film switch that is molded into a knobstructure; and

FIG. 6 is a cross-sectional view of a knob that incorporates the filmswitch of FIG. 5.

FIG. 7 illustrates a cross-sectional view of an in-molded resistiveelement including formed film layer including one or more conductive inktraces.

FIG. 8 depicts a cross-sectional view of an in-molded electromagneticshielding element including a formed film layer.

FIG. 9 illustrates an exploded view of an article of manufactureincorporating a film having a resistive element, an electromagneticshielding element, and/or a film switch printed on the film.

FIG. 10 illustrates an article of manufacture including a cellularantenna and an in-molded electromagnetic shielding element.

FIG. 11 depicts an article of manufacture including an RFID antenna andan in-molded electromagnetic shielding element.

DETAILED DESCRIPTION

The present disclosure relates to in-molded switch devices. Thepreferred embodiment is directed to capacitive switches which may bein-molded. Moreover, the capacitive switches may also be in-molded asthree dimensional structures. As mentioned above, capacitive switchingdetects changes in capacitance due to a disturbance that defines aswitching event. The present disclosure further relates to in-moldedresistive and shielding elements.

In one embodiment, when a conductive or charged object, such as afinger, is placed near a sensing zone, the sensing zone's capacitancechanges, indicating the occurrence of a switching event. The sensingzone's capacitance changes are detected by sensing circuitry. Thesensing circuitry can be tuned to detect specific changes incapacitance. For example, the sensing circuitry can be tuned to detectthe presence of a finger proximal a sensing zone, while not detectingother types of disturbances (e.g., moisture). Examples of capacitiveswitch sensing electronics are disclosed in, for example, U.S. Pat. No.5,972,623 to Gupta et al., filed Oct. 21, 1997, entitled “Solid statecapacitive switch,” the entire contents of which are incorporated byreference herein. Moreover, as discussed herein, the capacitive switchesmay be used to detect an object at a distance as well as a touch. Thesesensing operations are described in detail with respect to U.S. Pat.Nos. 5,730,165, 6,288,707, 6,377,009, 6,452,514, 6,457,355, 6,466,036,6,535,200, the entire contents of which are incorporated by referenceherein.

To integrate capacitive switches into three-dimensional supportstructures, it is desirable to provide a switch that can be contoured toa desired shape while still retaining its ability to detect capacitancechanges. It has been found that by printing capacitive switch elementson a film and molding the film with a plastic material, the switch canbe advantageously contoured to a desired shape. Such in-moldedcapacitive switches have numerous applications. For example, theswitches can be used in numerous automotive interior applications suchas center stack consoles (e.g., radio switches, HVAC switches,navigation switches, heated seat switches, etc.). Moreover, the switchescan be molded to appear flat (like a touch panel,) indented (to directthe user to the switch), or to look like a rotary knob (protrudingoutward from the surface).

In addition, the in-molded capacitive switches described herein can beused in overhead consoles (e.g., sunroof, map light, homelike switches),door trim (e.g., window and heated seat switches). Depending on theapplication, it may be preferable to take steps to ensure that theswitch can not accidentally be activated by touch alone. Otherapplications include exterior lighting switches on a vehicle instrumentpanel, A-pillar trim switches for operating power liftgates andliftglass, B-pillar switches for keyless entry appliques and interiorillumination (once the keyless entry is activated). Other applicationsmay include switches to control accessories (such as an IPOD®) that maybe included, for example, in the center console as a flip out module.

In addition to forming in-molded capacitive switches, the methodsdescribed herein can be used to form other types of contoured and rigidconnector structures. For example, typical door latches contain severalswitch functions (i.e. door ajar, door open, child security, O/Slock/unlock, I/S lock). Typically these connections are made with metalstampings, which lend themselves well to the application. However, withseveral switches and varying latch cover plastic thicknesses, it canbecome rather difficult to route these connections. The interconnectionsystem used in these applications could be replaced with printedconductive ink conductors. The use of conductive ink traces makes itsimpler to route the conductors in areas where it was not possiblebefore.

The present disclosure is not limited to automotive applications. Forexample, the switches described herein may be used with appliances withtouch type switch panels (i.e. microwaves, stoves, refrigerators,washers, dryers, blenders, tasters). Other examples may include consumerelectronics such as music players or laptop computers where the switchesmay be in-molded with the plastic housings of such devices. Thein-molded switch concept lends itself especially well to theseapplications given the trend to providing more rounded edges and threedimensional shapes. In addition, these switches will not wear out overtime like a membrane or dome type switch array.

In a preferred embodiment, a three-dimensional molded part is createdwhich includes one or more of the following features:

-   1. Complex shape;-   2. In-molded graphics for items such as switches;-   3. In-molded decorative surfaces (i.e. wood grain, chrome, paint    colors);-   4. In-molded conductive circuit traces and switches (electrodes);    and-   5. Termination and attachment methods from the in-molded conductive    inks to outer mating connection points.    As will be apparent, such three-dimensional shapes can have several    surfaces, where the surfaces are either flat, curved or a    combination of both.

A method of making an in-molded capacitive switch will now be described.Generally, the method comprises preparing a film switch by printing aconductive ink sensing zone on a formable film, forming the film to adesired shape, die-cutting the formed film, inserting the formed film inan injection mold, and introducing a molten plastic material into themold. Referring to FIG. 1, an exploded view of a film comprising a filmswitch 20 is described. In the embodiment of FIG. 1, film switch 20comprises a film 22 on which a variety of ink layers are printed. Theembodiment of FIG. 1 is directed to a keyless vehicle entry system. Film22 comprises a sheet of formable film. Exemplary films that are suitablefor use as film 22 include polycarbonate-based Makrofol® and Bayfol®films supplied by Bayer Films Americas of Berlin, Conn. The color,translucence, and/or transparency of film 22 may be selected based onthe desired application. However, in the embodiment of FIG. 1, film 22is a smoked black color that is preferably translucent and which allowsgraphic indicia printed on one side to be viewed on the other side.

As shown in FIG. 1, several layers of various inks 24, 26, 28, 30, 32,34, and 36 are printed on film 22 to give the part its decorativeappearance, to provide the graphics for the keyless functions, and toprovide the conductive switches (electrodes) for activation by a user. Awide variety of printing processes may be used to deposit the variousink layers, including without limitation screen printing, off-setprinting, gravure printing, flexographic printing, pad printing,intaglio printing, letter press printing, ink jet printing, and bubblejet printing. However, in the exemplary embodiment of FIG. 1, screenprinting is preferred.

Referring again to FIG. 1, ink layer 24 is applied to film 22 using aprinting process as described above. Ink layer 24 preferably includesinkless areas that define graphic indicia related to the desiredswitching function. Since the embodiment of FIG. 1 is directed tokeyless entry systems, the inkless areas 38 preferably definealpha-numeric characters. Next, a layer of white translucent ink 26 isprinted on top of inkless area 38 to give the graphic indicia a whiteappearance. Of course, other colors may be used if desired. Suitableinks for forming ink layers 24 and 26 include without limitationNoriphan® HTR, a solvent-based, one-component screen printing ink basedon a high temperature resistant thermoplastic resin which is supplied byProll KG of Germany, and Nazdar® 9600 Series inks with 3% catalyst,which are supplied by the Nazdar Company of Shawnee, Kans.

Next, a conductive ink ground layer 28 is printed on white ink layer 26.Ground layer 28 provides a barrier for the switch (electrode) traces toensure that inadvertent actuations do not occur by accidentally touchinga trace. The conductive ink used in ground layer 28 and the otherconductive ink layers (described below) is preferably formulated towithstand forming processes wherein film 22 is formed into a desiredshape. The conductive ink is also preferably formulated to withstandtypical injection molding temperatures and blow-off. One suitableconductive ink is DuPont Silver Conductor 5096, which is designed foruse in thermoforming operations or where extreme crease conditions areemployed on flexible substrates. Another example of a conductive ink isElectrodag® SP-405 available from Acheson. Colloids Company. Ground orshield layer 28 includes a plurality of unprinted (inkless) areas 40that define apertures which are sized to accommodate conductive inksensing zones 42 (discussed below).

Dielectric layer 30 is printed on ground layer 28 using a dielectric inkthat is formulated to withstand the film forming and molding processesdescribed below. Dielectric layer 30 is preferably configured to coverthe entire ground layer 28 and insulates conductive ink sensing zones 42and their associated electrodes from ground layer 28.

Switch layer 32 is then printed on dielectric layer 30. Switch layer 32is formed from a conductive ink of the type described above with respectto ground layer 28. Switch layer 32 also comprises a plurality ofsensing zones 42 which sense the presence of an object, finger, etc. atdifferent locations. As shown in the figure, sensing zones 42 arepreferably aligned in correspondence with one of the indicia 38 so thata user's selection of a particular one of the indicia is detected by acorresponding one of the sensing zones 42. Switch layer 32 alsocomprises a plurality of electrode traces 44, 46, 48, 50, and 52 whichallow each sensing zone 42 to be connected to a sensing circuit (notshown).

If desired, film switch 20 may include one or more LEDs to illuminateregions of film switch 20. In the embodiment of FIG. 1, LEDs (not shown)are provided to backlight each of the sensing zones 42 and graphicindicia 38. For a keyless entry application, LEDs are especially helpfulto allow the car owner to see the indicia 38 at night. LEDs may also beactivated in response the presence of a finger or object near filmswitch 20 so that as a person begins to execute keystrokes necessary tounlock the doors, graphic indicia 38 will become illuminated. The LEDsmay have their own dedicated sensing zone, or they may be activated inresponse to a switching event at one or more of the sensing zones 42. IfLEDs are used, dielectric layer 34 is preferably printed on switch layer32 using a dielectric ink to electrically isolate the LED circuit fromthe switch circuit (i.e., sensing zones 42 and electrodes 44, 46, 48,50, and 52).

To facilitate the foregoing printing processes, the film 22 preferablyremains substantially flat during the printing of ink layers 23 and 24.It should be noted that there can be multiple layering sequences otherthan those noted above to create the capacitive switch. For example, ifLED's are not desired, then the conductive layer may be removed from theprint layers stack-up. Alternatively, layers may be eliminated bycombining layers such as the electrode and LED layers. However, afterfilm switch 20 is prepared, it is preferably formed to a desired shapeand size. The desired shape is preferably selected based on thestructure into which it will be incorporated. Thus, for example, if thefilm switch 20 is to be used on a vehicle A-pillar, it is preferablyformed to have shape that conforms to the A-pillar shape.

Any suitable forming process which provides the desired shape withoutcompromising the integrity or performance of the ink layers can be usedto shape film switch 20. However, in a preferred embodiment, switch 20is shaped by thermoforming (vacuum) or pressure forming such as NieblingHPF (high pressure forming) or hydroforming. For applications in whichtightly registered (aligned) graphics are required, pressure forming ispreferred. However, in those applications where registered graphics arenot required, vacuum thermoforming may be suitable.

In a vacuum thermoforming process, a mold is provided that defines thedesired film shape. The mold may comprise cavities and/or raisedportions to define recessed surfaces and protruding surfaces,respectively, in the film. The film is then clamped in a frame andheated. Once a rubbery state is achieved (e.g., flexible, softened,supple, and the like), the film is placed over the mold cavity. Air isthen removed from the cavity via a vacuum, such that atmosphericpressure forces the film against the walls of the mold. Typical vacuumthermoforming temperatures are generally from about 180° C. to about200° C. with a temperature of about 190° C. being preferred. Typicalvacuum thermoforming pressures are about 1 Bar.

In the Niebling HPF process, high pressure air is used to force the filminto the mold, and a vacuum is not required. Details of exemplary highpressure forming processes are provided in U.S. Pat. No. 5,108,530, theentire contents of which are hereby incorporated by reference. In theNiebling HPF process, typical temperatures are from about 160° C. toabout 180° C. The process pressure is generally from about 100 Bar toabout 300 Bar.

Pressure forming processes using pressures lower than those in theNiebling process may also be used to form film 22 to the desired shape(such as the Hytech Accuform process). In one exemplary embodiment, film22 comprises a polycarbonate sheet. When polycarbonate sheets are used,typical forming parameters include a pressure of about 35 Bar, atemperature of about 160 to 180° C., a maximum draw depth of about 35-40mm, and an elongation ratio of about 3:1 to about 4:1.

The form tool is preferably designed to create a part where decorativefeatures are visible on the A-surface of film 22. In a preferredembodiment, the decorative features are printed on the B-surface of film22 and are visible on the A-surface. However, in other embodiments, thedecorative features may be printed on the A-surface of film 22.Generally, it is preferable to use a positive (i.e., male or protruding)tool as opposed to a negative (i.e., female or cavity) tool in the filmforming process to avoid contact between the film's A-surface and thetool surface, which can produce marks and surface wear on film 22. Itshould be understood however, that a negative tool can be used in theforming process instead. The cycle times, temperatures, and vacuum orpressures are preferably adjusted accordingly to ensure the part doesnot exhibit any cracking of inks or excessive stretching.

In a hydroforming process a diaphragm face of unpressurized fluid comesinto contact with the film surface. The diaphragm is contained within aframe that is matched to an embossing die (male tool). At theappropriate time the fluid is pressurized, which forms the film into thedesired shape based on the male tool on the other side of the film. Thediaphragm again is depressurized and the film can be released from thetool. The cycle times, temperatures, and pressures are preferablyadjusted accordingly to ensure the part does not exhibit any cracking ofinks or excessive stretching.

An embodiment of a film switch 20 after the forming operation isdepicted in FIG. 2A. As FIG. 2A indicates, film switch 20 includes acontoured region 54 that is produced by the forming operation. FIG. 2Ais a view of the “B-surface” of film switch 20, i.e., the surface thatfaces away from a user when film switch 20 is molded in a supportstructure. As shown in FIG. 2A, ink layers 23 are also contoured. Afterforming, film switch 20 is then cut to the desired shape. In anexemplary process, die cutting is used (e.g., using a column guidedpunching tool with a male and female die set).

FIG. 2B illustrates another embodiment of a film switch 20 including acontoured region 54 after the forming operation. Instead of showing theprinted layers flowing up and over the edge of the formed part, asdepicted in FIG. 2A, for the method of inserting the connector into themolded part (described in more detail below with respect to a switchtail configuration) the conducive layers of ink layers 23 are notprinted up over the formed edge to be die cut.

Following the forming of film switch 20, a three-dimensional,substantially rigid structure is formed which includes film switch 20 asa component. In a preferred embodiment, film switch 20 is athermoplastic material which is molded with heat and pressure into ashape via an injection molding process. Typical molding parameters varybased on the resins being molded. However, some examples of moldingparameters are provided. For urethanes (e.g., thermoplastic urethane or“TPU”) typical injection molding pressures range from about 5,000 toabout 8,000 PSI and the molding temperature ranges from about 380 toabout 410° F. For polycarbonates, typical injection molding pressuresrange from about 8,000 to about 15,000 PSI and the molding temperatureranges from about 540 to about 580° F. Of course, each material may havepreferred molding pressures or temperatures outside of the exemplaryranges provided.

A wide variety of thermoplastic materials may be used, including but notlimited to polycarbonates, acrylonitrile-butadiene-styrene (“ABS”)polymers, and polycarbonate blends such as polycarbonate-ABS,polycarbonate-polybutylene terephthalate, and polycarbonate-polyethyleneterephthalate. Specific examples of the foregoing polycarbonate blendsare those sold under the Makrolon® name by Bayer Films Americas. Incertain embodiments, the thermoplastic resin preferably has a melt flowindex of greater than about 20 as measured by the ISO 1133 or ASTMD-1238 procedures. In one exemplary embodiment, film 22 comprises apolycarbonate film and the thermoplastic comprises Makrolon®2405, whichhas an ASTM D-1238 melt flow index (300° C./1.2 kg) of 20. Exemplarythermoplastic urethanes include Texin® thermoplastic urethanes suppliedby Bayer MaterialScience LLC of Pittsburgh, Pa. One exemplary Texin®material is Texin® 245. Exemplary ABS materials include ABS materialssupplied by Lanxess Deutschland GmbH. Two exemplary ABS materialssupplied by Lanxess are Lustrant® LGA and Lustran® LGA-SF. In addition,acrylic materials such as Plexiglas® V052 a product of AltuglasInternational of Philadelphia, Pa. may be used. In certain embodiments,such as those using polycarbonates or thermoplastic urethanes, thethermoplastic material bonds well directly with the film. However, inother embodiments, an adhesion promoter may be required for improvedbonding with the film.

To form the desired part, a mold (not shown) is provided which isconfigured to accept and retain film switch 20. The mold preferablycomprises two halves (shells) that can be mated to define a mold cavityin which molten thermoplastic is injected. The mold cavity defines theshape of the part being formed. One of the mold halves is stationary andone is movable. Film switch 20 is preferably disposed in the stationarymold half and held in place by a press fit as the mold halves are matedprior to introducing the molten plastic.

In addition, the stationary mold half is preferably configured to retainfilm switch 20 such that the thermoplastic material can flow over it toyield part in which some or all of the A-surface (user-facing surface)of film switch 20 exposed. In certain embodiments, the graphics, sensingzones, and electrodes are less than 0.5 mm behind the exposed A-surfaceof film switch 20. Film switch 20 is preferably disposed in the moldsuch that printed ink layers 23 and 24 (FIG. 1) face into the moldinterior without contacting the mold surfaces. This processadvantageously produces a finished support structure that allows theuser to directly contact film switch 20, while still protecting the inklayers 23 and 24 from direct exposure to the environment. As a result,the A-surface of the finished part will appear to contain all thedecorative features such as switch graphics, simulated wood grain,chrome or other smooth or textured surfaces. However, these graphicswill actually be on the B-surface of the film, with the switch circuitprinted directly behind the graphic indicia portions. While it ispreferable to locate the ink components on the B-surface of film switch20, in certain embodiments the ink components may be located on theA-surface to face the user in an installed condition.

In an embodiment, connector terminals are provided to allow thein-molded capacitive switch to be removably connected to sensingelectronics or other electronic devices. The terminals are preferablydesigned to match the contoured, three dimensional shape of theB-surface of film switch 20. Each terminal is placed in the “movingside” of the injection mold. The terminal ends press fit into receiverpockets in the mold. This step may be completed as a hand or roboticprocess. Location may be established by a pocket in the moving mold halfand a locator pin (this can also be an ejector pin). A pressure zone(adhered to the terminal in advance) is another option for keeping theterminal in place.

A thin film (bead) of any type of conductive adhesive (i.e. silverfilled epoxy) is applied to the surface of each terminal connector suchthat it touches the conducive ink traces 44, 46, 48, 50, 52 (FIG. 1) onthe film switch 20 once the mold halves are mated. The application ofthe conductive adhesive may be completed by hand or roboticallyautomated. An example of conductive adhesive is CHO-BOND® 584 (availablefrom Chomerics) which combines the adhesive properties of epoxy with theconductivity of silver. Another method for insuring terminal attachment(i.e., connection) is using a B-stageable conductive epoxy that isprinted over the conductive traces in the printing process.

After applying the conductive adhesive to the connector terminals, theinjection mold is closed and the normal injection molding sequenceensues to cause the selected thermoplastic material to flow into themold cavity defined by the two mold halves. In this step the terminalsand conductive epoxy are pressed onto the silver ink traces 44, 46, 48,50, and 52 on film switch 20. Careful steps should be taken to ensurethat the injection molding process does not force the conductive epoxyto inadvertently flow into unwanted areas. The heat of the injectionmolding process actually cures the conductive epoxy in a short timeframe (at room temperature this process could take up to 24 hours). Thepart is then ejected from the mold. As a result of this process, thethermoplastic material holds the terminals in place. Thus, connector canbe molded directly into the plastic part.

In addition to providing terminals that are individually molded into thepart, a terminal block may also be provided. In this embodiment,multiple terminals are pre-molded into a terminal block, and the blockis then molded into the part. In certain variations, the terminal blockwill have a substantially flat surface that is connected to conductiveink traces 44, 46, 48, 50, and 52. However, a terminal block may also beprovided wherein individual terminals protrude from the block to connectto the conductive ink traces. An exemplary terminal block that issuitable for this embodiment is a BergStik® Unshrouded Header 54201connector supplied by FCI of Etters, Pa. The same methods of attaching aterminal block as previously described apply here (e.g., usingconductive epoxy).

It should be noted that there are several advantages to the type ofconductor arrangement described above. In certain embodiments, there isno piercing of the decorative film layer 22, thereby eliminating theneed for a wraparound film switch tail (however this is a viabletermination method, as described below). In other embodiments, terminalconnectors can be permanently fixed in place via an injection moldingprocess, minimizing the possibility of their becoming unattached fromthe silver ink through the conductive adhesive. The previously describedmolding process minimizes the likelihood of the conductive epoxycracking, which could degrade its performance. Further, the conductiveadhesive is cured quickly due to the heat transfer of the injectionmolding process. Normally, conductive adhesives such as epoxies arecured at room temperature or through infrared or ultrasonic curingmethods. However, they quickly cure at common injection moldingtemperatures, such as those described previously.

Alternatively, instead of using molded in connectors or connectorblocks, a flat flexible cable (e.g., a wraparound film switch tail or“pig-tail”) may also be used to connect switch layer 32 to sensingcircuitry or other electronic components. One exemplary flat flexiblecable connector is an FCI 65801 Clincher Receptacle. In this embodiment,the wrap-around switch tail is connected to conductive traces 44, 46,48, 50, and 52 and is molded into the part so that a free end of thetail extends from the part for connection to the sensing circuitry orother electronic components. This embodiment is depicted in FIG. 2B.Particularly, FIG. 2B illustrates the conducive layers of ink layers 23inserted into the molded part as opposed to printed over the formededge.

FIG. 4 depicts a cross-sectional view of a molded part 56 including acapacitive switch. As the figure indicates, connector terminal 60 isattached to one of the conductive ink traces 44, 46, 48, 50, 52 (FIG. 1)via a conductive adhesive 61. Molded plastic 58 surrounds a portion ofconnector terminal 60, thereby securely retaining it in molded part 56.It should be noted that although it is not shown, a female connectorhousing may be incorporated into the molded part to avoid the use ofterminals that protrude from the part. In this embodiment, a matingconnector is removably attached to the molded part after the moldingprocess is complete. The use of a female connector housing also protectsthe terminals from being damaged during manufacturing operations priorto attachment to the mating connector. In certain embodiments, themating connector is an individual component, while in other embodimentsit is incorporated into an electronic module that includes the sensingcircuitry for detecting switching events.

In another embodiment, instead of molding terminals 60 in molded plastic58, the part may be molded with voids that allow for subsequentattachment to connector terminals after the molding process. In thisembodiment, a close-out is provided in the injection mold to definevoids in the part. The voids are preferably in substantial alignmentwith conductive ink traces 44, 46, 48, 50, and 52. The connectorterminals are inserted into the voids and in contact with the conductiveink traces 44, 46, 48, 50, and 52. Any space around the connectorterminals is then filled with a suitable plastic material to sealconductive ink traces 44, 46, 48, 50, and 52. A conductive adhesive ofthe type described previously may also be used to connect the terminalsto the conductive ink traces 44, 46, 48, 50, and 52.

It is envisioned that the electronics associated with the capacitiveswitching would be directly connected to terminals 60 to provide for alow profile packaging concept. FIG. 4 shows molded part 56 from thebackside (B-surface) to show how the terminals 60 are positioned. Ofcourse, terminals 60 may be located anywhere on the back of the partbased on the application.

In contrast to many known processes, the foregoing process avoids theneed for providing separate graphic overlays to protect sensing zones 42and associated electrodes 44, 46, 48, 50, and 52. Because the filmswitch 20 is formed to a shape that corresponds to the desired supportstructure shape, the electrodes and sensing zones can be moreconsistently positioned at equal distances from the front surface of thearticle, thereby reducing variations in sensitivity amongst theindividual sensing zones and electrodes. When over-molding, all of theswitch elements including the electrodes and conductors are protectedfrom environmental concerns (i.e. humidity, salt exposure). Insertmolding the connector terminals 60 and sealing off directly around themminimizes these environmental issues.

If desired, LED's may be directly mounted on the conductive traces 44,46, 48, 50, 52, and over-molded. However, it may be desired to provide ashut-off in the mold (leaving the conductive traces slightly exposed).In one embodiment, the LED would be attached using conductive epoxy oran equivalent method. The void in the mold could then be filled withthermally conductive epoxy to seal the LED. It may be also beneficial tomount the LED as a secondary process if the LED requires light piping tospread the light output to a wider output pattern. In this case the LEDand light pipe (e.g., a light guide) assembly would be designed withleads that could be attached to the conductors. Another technique is toinsert a light pipe that can assist in lighting multiple areas with oneor more LED's. While this technique would require external connectionsto the LED's, it may prove cost beneficial.

An embodiment of an LED incorporated into a part with an in-moldedcapacitive switch is shown in FIG. 3, wherein LED 63 is molded into part56. A typical LED that would be suitable is an Osram type “point LED”part number LW P473. Modification to the packaging of the LED may berequired to ensure proper light output through the film and switchlogos. These types of LED's typically draw 15 mA or less which allowsfor encasing them in plastic resin without overheating the component orthe switch packaging. However, as mentioned previously, an alternativeto totally sealing them is to leave a void in the backside of the moldedpart 56 where each LED is located to dissipate the heat. The void ismade, for example, by including a core pin shut-off in the mold thatmates with the B-surface of the film. This area could then be sealedwith a thermally conductive epoxy which would prevent water intrusion.The process for the attachment to the conductors of such LED's would besimilar to the terminal attachment described in this section. Parts suchas the LED's may be, for example, hand inserted where pinpointconsistency of placement is not required. Alternatively, the LED's maybe robotically inserted (such as using a pick and place machine) forprecision or multiple component placement that would otherwise be toodifficult or costly to perform using hand placement.

The in-molded capacitive switches described herein can be used in anumber of different configurations and geometries. For example,conductors and electrodes can be formed into protruding or recessedshapes (for items such as knobs and buttons). The processes describedherein allow the switch components to be printed onto a flat film andthen formed to the desired shape. In addition, multi-segment sensingzones can be used.

In one embodiment, a molded knob is created which allows a user tooperate a device such an HVAC system, radio, CD player, etc. by movinghis fingers around the circumference of the knob. An embodiment of aknob with an in-molded capacitive switch is depicted in FIGS. 5 and 6.Knob 62 is a generally cylindrical structure that is preferably moldedfrom a plastic material and which includes a user contact surface 65 fortriggering switching events. Film switch 64 generally comprises a seriesof printed ink layers on a film as described previously. FIG. 5 depictsa plan view of film switch 64 with sensing zones 66 and electrodes 68(ground layers, dielectric layers and graphic layers are not shown),prior to a forming operation. Sensing zones 66 and electrodes 68 areprinted using a conductive ink and printing process of the typedescribed previously. Film switch 64 is preferably formed to the desiredknob shape using a suitable forming process such as vacuumthermoforming. Like the previous embodiment, film switch 64 ispreferably disposed in a stationary mold half such that the printed inklayers face into the mold cavity and avoid contact with the mold walls.The stationary mold half preferably defines a shape into which filmswitch 64 fits so that molten plastic may be injected over it. The inklayers that define sensing zones 66 and electrodes 68 preferably faceinto the mold cavity and do not contact the mold surfaces. Thus, as withthe previous embodiment, the user exposed surface (A-surface) of theresulting structure comprises the A-surface of film switch 64. As shownin FIG. 6, in one embodiment, sensing zones 66 each define an L-shapedcross-section around the periphery of knob 62.

Knob 64 is preferably stationary. However, it allows the user tosimulate rotation by triggering different switching events as the user'sfingers traverse the knob's circumference, which causes capacitancechanges at each successive sensing zone 66. As with the previousembodiments, connector terminals may be connected to electrode traces 68via a conductive adhesive and molded into knob 64 to allow for removableconnection to sensing circuitry or other electronics.

The resistive properties of the conductive ink can also be used toprovide a voltage drop in circuits, to provide a heating device, or toprovide an antenna. FIG. 7 illustrates a cross-sectional view of anin-molded resistive element part 74 including a formed film layer 70 onwhich one or more conductive ink traces 76 are printed. The formed filmlayer 70, in turn, is overlaid on molded plastic part 78 such that theformed film layer 70 has one side exposed, a portion of one sideexposed, or both sides are in-between the top and bottom of the moldedplastic part 78. Either side of the formed film layer 70 can face theinterior of the molded plastic part 78. Conversely either side of thefilm layer 70 can be disposed to the exterior of the molded plastic part78. In terms of the A and B-surfaces of the formed film layer 70 and themolded plastic part 78, the A-surface or B-surface of the formed filmlayer can be disposed on the A-surface or B-surface of the moldedplastic part 78.

A connection point 72 (i.e., an exposed area of conductive ink) isprovided on the surface of the film. Connection point 72 can then beused to connect the resistive element to another device, circuit orcomponent. Connections to connection point 72 can be made by, forexample, a spring-clip connector, rivet connector, and the like. Inaddition, a pig-tail type connector as discussed above can by used as analternative. Alternatively, connection point 72 can be used to connectother conductive ink traces on the same printed and formed film layer 70(not shown). These additional traces can be printed on a layer separatedby, for example, a non-conductive layer such as a dielectric layer.

As discussed above, LEDs can be directly mounted on the conductivetraces 76 and over-molded or surface-mounted using conductive epoxy, oran equivalent technique. Alternatively, the resistive element or tracedesign may serve as a heating component or as an antenna. In addition,the resistive elements may be part of a circuit also formed ofconductive ink, such as an RC circuit, where both the resistor andcapacitor of the RC circuit are formed at least in part of conductiveink. Film switch 20 described above with respect to FIG. 1 also can beprinted on the same formed film layer 70. In addition, a dielectriclayer can be constructed on either the front or back surface of theformed filled layer 70 to provide a coating over some or the entiresurface. This dielectric coating can be used to protect an exposedsurface or to provide a non-conductive layer between two ink layers.

The resistance of the conductive ink traces 76 is based on theohms/square inch of the conductive ink, the thickness of the conductiveink traces 76 and the width and length of the conductive ink traces. Theconductive ink traces 76 can thus be formed to provide differentresistances. In one embodiment, the resistive elements can be used toprovide a voltage drop to a device such as an LED.

The pattern of the resistive elements formed by conductive ink traces 76also is a design choice. For example, conductive ink traces 76 may bearranged as a sine wave, a triangle, or zig-zag pattern. In addition,the layout of conductive ink traces 76 can be based upon the number ofrequired connection points 72, or whether the resistive elements are tobe connected serially or in parallel.

In another embodiment, the conductive ink traces 76 can be utilized toprovide a tamper detection circuit, which detects a drop in voltagecaused by a corresponding decrease in resistance of the in-moldedresistive element 74 upon a break or puncture in film layer 70.Alternatively, a resistive element 74 can be designed to be tamperresistant, such that electrical connectivity is maintained if someoneattempts to drill into or otherwise break or puncture the film layer 70.

As mentioned above, the conductive ink traces 76 can be used as heatingelements. This configuration can be used to provide heat to, and thuscontrol the temperature of, components affixed to or near the heatingelements.

In yet another embodiment, an electromagnetic shielding element (or RFshield) is formed of conductive ink. Radiation of electromagnetic energymay be released from an electronic device. Some electronic devicesgenerate sufficiently strong electromagnetic fields that propagate awayfrom the device as to interfere with other electronic devices orotherwise cause problems. While radiated emissions are usuallyassociated with non-intentional radiators, intentional radiators canalso have unwanted emissions at frequencies outside their intendedtransmission frequency band. It is thus desirable to provide anelectromagnetic shielding element to prevent radiation from exiting thedevice. Alternatively, it is desirable to provide an electromagneticshielding element to prevent radiation from external sources fromentering the device.

Ground or shield layer 28 of FIG. 1 may act as an electromagneticshield. This property allows ground or shield layer 28 to inhibit theexit or entry of radiated emissions caused by electrical componentswithin or outside of a device, respectively.

FIG. 8 depicts a cross-sectional view of an in-molded electromagneticshield part 80 including formed film layer 82 on which conductive inktraces 86 arranged in a grid pattern are printed. As described above,the conductive ink traces 86 provide a shielding layer to inhibit theexit or entry radiated emissions. The formed film layer 82 containingconductive ink traces 86 is shown completely covering a molded plasticpart 88.

Either side of the film layer 82 can be disposed to the interior orexterior of the molded plastic part. Thus, in terms of the A andB-surfaces of the formed film layer 82 and the molded plastic part 88,the A-surface or B-surface of the formed film layer 82 can be disposedon the A-surface or B-surface of the molded plastic part 88.

In another embodiment, formed film layer 82 can be constructed to wraparound edges of molded plastic 88, as shown in FIG. 8. Alternatively,formed film layer 82 may form an electromagnetic shield partiallycovering molded plastic 88. The formed film layer 82 also can beexposed, partially exposed or in-between the top and bottom of themolded plastic part 88. In addition, a dielectric layer can beconstructed on either the front or back surface of the formed film layer82 to provide a coating over some or all of the surface. This dielectriccoating can be used to protect an exposed surface or to provide anon-conductive layer between two ink layers.

The pattern of the shielding element formed by conductive ink traces 86is a design choice. For example, the conductive ink traces 86 may bearranged in a grid pattern or as a solid sheet of ink. Additionally,conductive ink traces 86 can vary in thickness or in pattern throughoutformed film layer 82, to selectively inhibit radiation from differentelectromagnetic fields or at different frequencies or frequency bands,thereby creating different shielding footprints.

As shown in FIG. 8 a connection point 84 (i.e., an exposed area ofconductive ink) is provided on the surface of the film. Connection point84 can be used to connect the shielding element to another device,circuit or component. Connections to connection point 84 can be made by,for example, a spring-clip connector, rivet connector, and the like. Inaddition, a pig-tail type connector as discussed above can by used as analternative. Alternatively, connection point 84 can be used to connectother conductive ink traces on the same printed and formed film layer 82(not shown). These additional traces can be printed on a layer separatedby, for example, a non-conductive layer such as a dielectric layer.

FIG. 9 illustrates an exploded view of an article of manufacture 74incorporating a film 20 having a resistive element and a film switchprinted on a layer on the film 20 (shown collectively as ink layer 90).Film 20 can be inserted in a molded part 92 such that the printed inklayer faces into a mold cavity (or B-surface) and is not exposed afterthe molded part is formed. Alternatively, film 20 can be inserted inmolded part 92 such that the printed ink layer faces the other way andis exposed.

In still another embodiment, either surface of film 20 can be disposedon the A-surface (i.e., exterior) of the molded part 92 as describedabove.

In yet another embodiment, film 20 can be inserted in-between the topand bottom of the molded part such that neither side is exposed or suchthat only a portion of the film is exposed. If necessary, the film canbe inserted to avoid contact with the mold walls.

With reference also to FIGS. 7 and 8, in another embodiment, conductiveink traces that form an electromagnetic shielding element (FIG. 8, 86)can be substituted for the conductive ink traces that form the resistiveelement (FIG. 7, 76).

Resistive element, switch and/or electromagnetic shielding element alsocan be printed on the same layer. Or, they can be formed of differentink layers, separated by a non-conductive layer such as a dielectriclayer.

Optionally, resistive element 74 (or electromagnetic shielding element80) can be decorated with graphics, such as numbers, representativepictures, illustrations, and the like. Decoration of resistive element74 or in-molded electromagnetic shielding element 80 may be accomplishedutilizing various methods, including painting, laser etching, or otherprinting processes.

Alternatively, decoration of resistive element 74 or electromagneticshielding element 80 may be accomplished by layering a decorated filmlayer on the front or back surface of resistive element 74 orelectromagnetic shielding element 80. Backlighting can also be providedbehind resistive element 74 or electromagnetic shielding element 80.

FIG. 10 depicts an article of manufacture which serves as a cellularantenna and shielding element 1000. In this embodiment, the design ofconductive ink traces are printed on formed film layer 1010 to create acellular antenna array 1002 and a shielding element 1000. Both thecellular antenna array 1002 and the shielding element 1000 can beconstructed of the same ink layer or can be constructed of two separateink layers separated by a non-conductive layer such a dielectric layer.The formed film layer 1010 of this embodiment is overlaid on moldedplastic 1008. Film layer 1010 can be inserted in molded part 1008 suchthat the printed ink layer faces into a mold cavity (or B-surface) andis not exposed after the molded part is formed. Alternatively, filmlayer 1010 can be inserted in molded part 1008 such that the printed inklayer faces the other way and is exposed. In yet another embodiment,film layer 1010 can be inserted in-between the top and bottom of themolded part 1008 such that neither side is exposed or such that only aportion of the film is exposed.

Similarly, either the A-surface or the B-surface of film layer 1010 canbe disposed on the outside (or A-surface) of the molded plastic 1008.

As shown, both the electromagnetic shielding layer 1006 and the cellularantenna array 1002 are exposed. Alternatively, electromagnetic shieldinglayer 1006 may completely or partially, or not at all cover cellularantenna array 1002 on one or more sides. Such a configuration can beaccomplished by printing the cellular antenna array 1002 and theelectromagnetic shielding layer 1006 on different ink layers andseparating them by a non-conducted layer such as a dielectric layer. Theabove-described shielding embodiments can be configured to permit thecellular antenna array 1002 to radiate away from the device whileprotecting the circuits or persons on the other side of the array fromthat radiation.

As shown in FIG. 10 a connection point 1004 (i.e., an exposed area ofconductive ink) is provided on the surface of the film. As describedabove, connection point 1004 can be used to connect the antenna and/orshielding element to another device, circuit or component. Connectionsto connection point 1004 can be made by, for example, a spring-clipconnector, rivet connector, and the like. In addition, a pig-tail typeconnector as discussed above can by used as an alternative.Alternatively, connection point 1004 can be used to connect otherconductive ink traces on the same printed and formed film layer 1010(not shown). These additional traces can be printed on a layer separatedby, for example, a non-conductive layer such as a dielectric layer.

FIG. 11 depicts an article of manufacture 1100 which serves as an RFIDantenna 1106 and electromagnetic shielding layer 1108. The RFID antenna1 106 and electromagnetic shielding layer 1108 are constructed ofconductive ink printed on a formed film layer 1112 and is attached to apassive RFID circuit 1104. As shown in FIG. 11, an electromagneticshielding layer 1108 is incorporated around the RFID antenna 1106 inthis embodiment. This can be accomplished by printing one layerincluding both the electromagnetic shielding layer 1108 and the RFIDantenna 1106 or by printing multiple layers separated a non-conductivelayer such as a dielectric.

As shown in FIG. 11 a connection point 1102 (i.e., an exposed area ofconductive ink) is provided on the surface of the film. As describedabove, connection point 1102 can be used to connect the RFID antennaand/or shielding element to another device, circuit or component.Connections to connection point 1004 can be made by, for example, aspring-clip connector, rivet connector, and the like. In addition, apig-tail type connector as discussed above can by used as analternative. Alternatively, connection point 1004 can be used to connectother conductive ink traces on the same printed and formed film layer1112 (not shown). These additional traces can be printed on a layerseparated by, for example, a non-conductive layer such as a dielectriclayer.

Another shielding ink layer could be formed beneath the RFID antenna1106 (not shown). This other shield would allow the RFID antenna 1106 toradiate away from the device while protecting the circuits or persons onthe other side of the antenna from that radiation.

Film layer 1112 can be inserted in molded part 1110 such that theprinted ink layer faces into a mold cavity (or B-side) and is notexposed after the molded part is formed. Alternatively, film layer 1010can be inserted in molded part 1110 such that the printed ink layerfaces the other way and is exposed.

In yet another embodiment, film layer 1112 can be inserted in-betweenthe top and bottom of the molded part 1110 such that neither side isexposed or such that only a portion of the film is exposed.

Either side of the film layer 1112 can be disposed to the interior orexterior of the molded plastic part. Thus, in terms of the A andB-surfaces of the formed film layer 1112 and the molded part 1110, theA-surface or B-surface of the formed film layer 1112 can be disposed onthe A-surface or B-surface of the molded plastic part 1110.Alternatively, the electromagnetic shielding layer 1108 may or may notbe utilized. The electromagnetic shielding layer 1108 may have anopening for the RFID antenna 1106. Alternatively, electromagneticshielding layer may completely cover RFID antenna 1106.

The present invention has been particularly shown and described withreference to the foregoing embodiments, which are merely illustrative ofthe best modes for carrying out the invention. It should be understoodby those skilled in the art that various alternatives to the embodimentsof the invention described herein may be employed in practicing theinvention without departing from the spirit and scope of the inventionas defined in the following claims. The embodiments should be understoodto include all novel and non-obvious combinations of elements describedherein, and claims may be presented in this or a later application toany novel and non-obvious combination of these elements. Moreover, theforegoing embodiments are illustrative, and no single feature or elementis essential to all possible combinations that may be claimed in this ora later application.

With regard to the processes, methods, heuristics, etc. describedherein, it should be understood that although the steps of suchprocesses, etc. have been described as occurring according to a certainordered sequence, such processes could be practiced with the describedsteps performed in an order other than the order described herein. Itfurther should be understood that certain steps could be performedsimultaneously, that other steps could be added, or that certain stepsdescribed herein could be omitted. In other words, the descriptions ofprocesses described herein are provided for illustrating certainembodiments and should in no way be construed to limit the claimedinvention.

Accordingly, it is to be understood that the above description isintended to be illustrative and not restrictive. Many embodiments andapplications other than the examples provided would be apparent to thoseof skill in the art upon reading the above description. The scope of theinvention should be determined, not with reference to the abovedescription, but should instead be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. It is anticipated and intended that futuredevelopments will occur in the arts discussed herein, and that thedisclosed systems and methods will be incorporated into such futureembodiments. In sum, it should be understood that the invention iscapable of modification and variation and is limited only by thefollowing claims.

All terms used in the claims are intended to be given their broadestreasonable constructions and their ordinary meanings as understood bythose skilled in the art unless an explicit indication to the contraryis made herein. In particular, use of the singular articles such as “a,”“the,” “said,” etc. should be read to recite one or more of theindicated elements unless a claim recites an explicit limitation to thecontrary.

What is claimed is:
 1. An electromagnetic shield, comprising: a filmhaving a conductive ink shielding layer printed on a surface of saidfilm; and a plastic support structure surrounding at least a portion ofthe film, wherein the film is secured to the plastic support structure.2. The electromagnetic shield of claim 1, the surface of said filmhaving an A-surface and a B-surface, wherein at least one of theA-surface and the B-surface of the film is secured to at least one of anA-surface and a B-surface of the plastic support structure.
 3. Theelectromagnetic shield of claim 1, wherein said film is in-between a topof the plastic support structure and a bottom of the plastic supportstructure.
 4. The electromagnetic shield of claim 1, wherein the film issecure to the plastic support structure to form a three dimensionalobject having a plurality of surfaces, the surfaces being at least oneof a flat surface and a curved surface.
 5. A resistive element,comprising: a film having a conductive ink resistive layer printed on asurface of said film; and a plastic support structure surrounding atleast a portion of the film, wherein the film is secured to the plasticsupport structure.
 6. The resistive element of claim 5, the surface ofsaid film having an A-surface and a B-surface, wherein at least one ofthe A-surface and the B-surface of the film is secured to at least oneof an A-surface and a B-surface of the plastic support structure.
 7. Theresistive element of claim 5, wherein said film is in-between a top ofthe plastic support structure and a bottom of the plastic supportstructure.
 8. The resistive element of claim 5, wherein the film issecured to the plastic support structure to form a three dimensionalobject having a plurality of surfaces, the surfaces being at least oneof a flat surface and a curved surface.